Elsevier

Livestock Science

Volume 211, May 2018, Pages 66-74
Livestock Science

Expected value of crossbred dairy cattle artificial insemination breeding strategies in virgin heifers and lactating cows

https://doi.org/10.1016/j.livsci.2018.03.005Get rights and content

Highlights

  • Crossbreeding may ease some economic pressure related to poor dairy reproduction.

  • Shifts towards crossbred dairy cattle will come with tradeoffs.

  • Producers should select for optimal farm profitability, not maximum production.

  • Improvements in reproductive performance are a key factor to consider.

Abstract

Research on sexed semen breeding techniques has largely focused on purebred cattle production systems and little work has been done evaluating sexed semen use in crossbred dairy cattle. Complementing a crossbreeding reproduction strategy with sexed semen artificial insemination (AI) has the potential to increase profit potential of sexed semen technology in the short and long run. The objective of this project was to estimate and compare the expected net present value (NPV) of reproduction management programs considering several conventional and sexed semen breeding strategies, cow ages, and breed compositions. While the potential benefits of sexed semen are varied, it is important to note that the focus of this study is on the economic returns to the breeding program. This is not a life-cycle analysis, and therefore, only the sexed semen costs and returns that directly impact the returns to the breeding program are considered. Specifically, a NPV model that incorporates dystocia and stillbirth costs, in addition to improved fertility of crossbred cattle (over purebred cattle), directly into the expected NPV calculation is developed. Increased use of crossbred dairy cattle in the United States make this research particularly timely and relevant. Consistent with previous research, results indicate that pure conventional semen AI and a mixed strategy with one sexed semen AI followed by conventional semen were generally the preferred breeding strategies in terms of expected NPV across all breeds and dam ages evaluated. Similarly, our results also support previous findings that the expected NPV of breeding programs for virgin heifers were consistently higher than lactating cows. In terms of breeds, the crossbreed scenarios generally produced higher expected NPV than scenarios for purebred Holsteins. The most influential factors resulting in these higher returns were the higher cumulative pregnancy rates associated with the crossbreds. Reproductive benefits of crossbred dairy cattle may be able to alleviate some economic pressure currently associated with poor dairy reproduction with AI breeding strategies (especially those incorporating sexed semen). However, it is important to note the likely tradeoffs associated with improvements in fertility (e.g., reduced milk production), the consideration of which is necessary to maximize whole farm profitability.

Introduction

Implementing new, efficient technologies is an effective strategy for optimizing milk production, and more importantly maximizing farm profitability (Olynk and Wolf, 2007). One such technology is sexed semen artificial insemination (AI) which may increase the productivity of farm assets (i.e., dairy herd) by improving reproductive efficiency. However, producers would only be expected to use this technology if the economic benefits outweigh the costs of implementation.

Sex-sorting semen uses fluorescence activated cell sorting to separate X- (male) and Y-bearing (female) sperm cells (Weigel, 2004). The method is fairly accurate with approximately 90% of the sperm containing the desired sex (Seidel and Schenk, 2002). Sexed semen provides dairy farmers the opportunity to increase dairy herd expansion rates and dairy productivity through genetic progress without compromising biosecurity from purchasing heifers outside of the farm (Weigel, 2004). Therefore, the potential benefits of sexed semen utilization are many and varied depending on the farms objectives for implementing this technology, including production of heifers from selected dams, production of excess heifers than can then be selected using genomic tests, and production of males from a selected bull mother. In addition, increasing the proportion of heifer calves may decrease incidence of dystocia (because heifer calves are generally smaller than bull calves) and stillborn calves (Bellows et al., 2002, Hansen, 2006).

While sexed semen can contribute positively to many dairy farms, sperm sex sorting process efficiency, semen price, and dairy dam conception rate (CR) are challenges associated with sexed semen. Most notably, sexed semen contain a lower concentration of sperm per straw (~2 million) than conventional semen (~20 million) because of the relatively slow sorting process, resulting in lower CR (DeJarnette et al., 2009). As a result, previous research has generally indicated that sexed semen AI is more likely to generate positive economic returns when used in virgin dairy heifers than in lactating dairy cows given their overall cleaner reproductive tract (Olynk and Wolf, 2007, DeJarnette et al., 2009).

Research on sexed semen breeding techniques, to date, has largely focused on purebred cattle production systems, and little work has been done evaluating the implementation of sexed semen AI in crossbred dairy production systems (Mellado et al., 2010). The potential for integration of sexed semen into crossbred cattle systems is notable because of the well established reproductive benefits of heterosis, or hybrid vigor (Heins, 2014). For example, in addition to increasing cow longevity and decreasing calving difficulties (Hansen, 2006) and incidence of stillborn claves (Weigel, 2005), crossbred dairy females are also known to have improved fertility (higher CR) (Heins, 2014). Therefore, complementing sexed semen AI with a crossbreeding reproduction strategy has the potential to improve CR of both virgin heifers and lactating cows resulting in increased profit potential of sexed semen technology in the short and long run.

The objective of this project is to estimate and compare the expected net present value (NPV) of reproduction management programs considering several conventional and sexed semen breeding strategies, cow ages, and breed compositions. In this analysis, we focus specifically on the economic costs and returns that are directly associated with reproduction performance. This is not a life-cycle analysis of the benefits of sexed semen. A full life-cycle analysis would provide a more holistic view of the economic value of sexed semen to dairy farmers, but unfortunately, such an approach is currently infeasible given a lack of sufficient data. Instead, the purpose of this research is to contribute to an existing body of knowledge by extending previously available economic support tools for dairy farmers who are considering the use of sexed semen AI and/or a crossbreeding strategy as a part of their dairy breeding program. This work develops a model that incorporates dystocia and stillbirth costs, in addition to improved fertility of crossbred cattle (over purebred cattle) directly into the expected NPV calculation. Previous work has ignored or overlooked potential dystocia and stillbirth cost savings associated with altered sex ratios of calves, as well as the impact of improved fertility of crossbred dairy cattle. Increasing use of crossbred dairy cattle in the United States makes this research particularly timely and relevant (Brazil and Rogers, 2017).

Section snippets

Materials and methods

Expected NPV analysis was used to measure and compare the profitability of implementing sexed semen AI in dairy reproductive management programs. The model evaluates the expected NPV of adopting sexed semen AI relative to a conventional semen reproductive program. Dairy reproductive assumptions and associated economic outcomes were obtained and used to determine the expected NPV for several reproductive program scenarios.

Results and discussion

The expected NPV and cumulative pregnancy rate for the 24 dairy reproductive program scenarios are reported in Table 7 for two feed cost scenarios ($0.15 and $0.22/kg dry matter) to evaluate the impact of feed cost on the returns to reproductive program scenarios. For simplicity, the discussion below focuses on the results from $0.15/kg dry matter feed cost scenario unless noted otherwise, and a discussion of the impact of fluctuations in feed price is provided in the Sensitivity Analysis–Feed

Conclusion

Results indicate that, consistent with previous research, pure conventional semen artificial insemination and the mixed strategy with one sexed semen artificial insemination followed by conventional semen were generally the preferred breeding strategies in terms of expected net present value across all breeds and dam ages evaluated. Inclusion of dystocia cost, which had been ignored in previous research, was not an important factor in determining the returns to reproductive program scenarios.

Conflicts of interest

None.

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